Prior studies investigating the interaction between PI3K pathway signaling and AR activity in cell lines and genetically engineered mouse models described a correlation between PTEN loss and decreased AR activity. We are using patient derived xenografts and organoid cultures from these lines to confirm the relevance to human disease, and to investigate the mechanism underlying reciprocal regulation of AR and PI3K activity. We have created inducible knockdown and expression constructs that will be used in this study, and we have established mouse models representing varying PTEN status seen in human disease.